1. Field of the Invention
The present invention generally relates to a cordless modem and, more particularly, to a high-speed, cordless data/facsimile modem wirelessly connecting a portable computer modem to a nearby telephone jack.
2. Background Description
Many personal computers (PCs) are equipped with a modem which permits data communications to other computers via standard telephone lines. A modem converts and compresses a high-speed, digital, serial data stream from a computer into a complex analog modulated signal that can be carried on standard telephone line. Present modem technology makes it possible to send data streams as fast as 28.8 kbps over the telephone network. Modern modems and modem software enable the modem to perform additional functions such as the ability to send and receive facsimile data. Modems with facsimile capabilities are typically referred to simply as data/fax modems.
Standard PCs, are typically situated at fixed location, such as a desk-top, and are not moved very often. A modem, either internal or external to the PC, is physically connected to a standard modular telephone wall jack via a telephone cord. Hence, the user is required to operate the computer in the proximity of a phone outlet or telephone wall jack since, the user's computer is physically tied to the wall. Cord connections work well for most desk-top PCs installations without many drawbacks, except that perhaps a telephone wall jack may need to be installed so as to avoid running a long extension cord around the room.
Telephone cords are, however, undesirable for portable or mobile computers, such as, for example, lap-tops, palm-tops, and notebooks, which enable computing anytime, anywhere. Many public facilities, such as hotels, and convention centers, provide telephone data jacks into which its patrons can plug their mobile computer's modem to gain access to the telephone network. However, often these jacks are in inconvenient places which require long cords to be routed across isles and walkways. This is potentially dangerous situation since not only may passersby trip on the cord and be hurt, but damage may result to the computer or modem in the process. Even in a private home or office situation, it would be nice to be able to roam from room-to-room without being encumbered by a cord.
In order to eliminate this problem and in order to further facilitate the growing demand for mobile computing there has been significant development of technology to provide wireless access to the telephone system. Today, cellular modems exist which provide wireless connectivity to cellular networks. For example, U.S. Pat. Nos. 4,972,457 and 5,353,334 to O'Sullivan, U.S. Pat. No. 5,020,090 to Morris, U.S. Pat. No. 5,408,520 to Clark et al., and European Patent Application 0,622,924 to Harrison are all directed to cellular modems. Normally, modems of this type are not themselves cellular, but rather, are simply adapted to plug into the user's cellular telephone which actually communicates with the cellular base station.
Cellular modems offer great freedom for mobile computers since they can connect to the telephone network over a wide geographic area. The user is typically within several kilometers of a cellular base station which in turn is connected to a standard land-line telephone network.
Unfortunately, there are numerous disadvantages to cellular modems. Not the least of which is that the user must be a subscriber to a cellular service and pay charges for the connection. This tends to be expensive. The cellular modem hardware is constructed to comply with the requirements of a particular cellular network, such as the AMPS (Advanced Mobile Phone System) cellular network, and therefor tends to be expensive. Cellular modems are most convenient and cost effective only for those mobile users that are far from standard telephone lines.
As is readily apparent, a more convenient, less expensive means for cordless interconnection to standard telephone lines is needed.